Research directed by C. Daehler (UH Botany) with funding from the Kaulunani Urban Forestry Program and US Forest Service

Information on Risk Assessments
Original risk assessment

Psidium guajava

Answer

1.01

Is the species highly domesticated?

y=-3, n=0

n

1.02

Has the species become naturalized where grown?

y=-1, n=-1

y

1.03

Does the species have weedy races?

y=-1, n=-1

n

2.01

Species suited to tropical or subtropical climate(s) (0-low; 1-intermediate; 2-high) – If island is primarily wet habitat, then substitute “wet tropical” for “tropical or subtropical”

See Append 2

2

2.02

Quality of climate match data (0-low; 1-intermediate; 2-high) see appendix 2

2

2.03

Broad climate suitability (environmental versatility)

y=1, n=0

y

2.04

Native or naturalized in regions with tropical or subtropical climates

y=1, n=0

y

2.05

Does the species have a history of repeated introductions outside its natural range? y=-2

?=-1, n=0

y

3.01

Naturalized beyond native range y = 1*multiplier (see Append 2), n= question 2.05

y

3.02

Garden/amenity/disturbance weed y = 1*multiplier (see Append 2)

n=0

n

3.03

Agricultural/forestry/horticultural weed y = 2*multiplier (see Append 2)

n=0

y

3.04

Environmental weed y = 2*multiplier (see Append 2)

n=0

y

3.05

Congeneric weed y = 1*multiplier (see Append 2)

n=0

y

4.01

Produces spines, thorns or burrs

y=1, n=0

n

4.02

Allelopathic

y=1, n=0

y

4.03

Parasitic

y=1, n=0

n

4.04

Unpalatable to grazing animals

y=1, n=-1

4.05

Toxic to animals

y=1, n=0

n

4.06

Host for recognized pests and pathogens

y=1, n=0

y

4.07

Causes allergies or is otherwise toxic to humans

y=1, n=0

n

4.08

Creates a fire hazard in natural ecosystems

y=1, n=0

4.09

Is a shade tolerant plant at some stage of its life cycle

y=1, n=0

n

4.1

Tolerates a wide range of soil conditions (or limestone conditions if not a volcanic island)

y=1, n=0

y

4.11

Climbing or smothering growth habit

y=1, n=0

n

4.12

Forms dense thickets

y=1, n=0

y

5.01

Aquatic

y=5, n=0

n

5.02

Grass

y=1, n=0

n

5.03

Nitrogen fixing woody plant

y=1, n=0

n

5.04

Geophyte (herbaceous with underground storage organs -- bulbs, corms, or tubers)

y=1, n=0

n

6.01

Evidence of substantial reproductive failure in native habitat

y=1, n=0

n

6.02

Produces viable seed.

y=1, n=-1

y

6.03

Hybridizes naturally

y=1, n=-1

6.04

Self-compatible or apomictic

y=1, n=-1

y

6.05

Requires specialist pollinators

y=-1, n=0

n

6.06

Reproduction by vegetative fragmentation

y=1, n=-1

n

6.07

Minimum generative time (years) 1 year = 1, 2 or 3 years = 0, 4+ years = -1

See left

3

7.01

Propagules likely to be dispersed unintentionally (plants growing in heavily trafficked areas)

y=1, n=-1

y

7.02

Propagules dispersed intentionally by people

y=1, n=-1

y

7.03

Propagules likely to disperse as a produce contaminant

y=1, n=-1

n

7.04

Propagules adapted to wind dispersal

y=1, n=-1

n

7.05

Propagules water dispersed

y=1, n=-1

n

7.06

Propagules bird dispersed

y=1, n=-1

y

7.07

Propagules dispersed by other animals (externally)

y=1, n=-1

n

7.08

Propagules survive passage through the gut

y=1, n=-1

y

8.01

Prolific seed production (>1000/m2)

y=1, n=-1

y

8.02

Evidence that a persistent propagule bank is formed (>1 yr)

y=1, n=-1

n

8.03

Well controlled by herbicides

y=-1, n=1

8.04

Tolerates, or benefits from, mutilation, cultivation, or fire

y=1, n=-1

y

8.05

Effective natural enemies present locally (e.g. introduced biocontrol agents)

y=-1, n=1

n

Total score:

21

Source

Notes

1.01

(1) 'A sporadically occurring small leafed form of the common guava is referred to as Dr. Rant's guava (Psidium guajava f. cujavillus.). (2) There are several cultivars of guava listed by this author but none of them appear to be wild.

(1) Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu. (2) Yadava, U. L. 1996. Guava (Psidium guajava L.): An exotic fruit with potential in the southern United States. HortScience Vol 31(5): 789 - 794.

1.02

It is naturalized in Hawai‘i and elsewhere

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu.

1.03

Wagner et al reported the sporadic occurrence of a variety called P. guajava f cujavillu in Hawaii (see 1.01). However it is probably not weedy (its occurrence seems to be sporadic).

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu.

2.01

'It is indigenous us to the American tropics, and is now naturalized throughout the tropics and subtropics.'

CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.

2.02

In addition to being cultivated for its fruits it has naturalized throughout the tropics and subtropics. The native and introduced regions are well known.

CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.

2.03

'P. guajava thrives in both humid and dry climates at an altitude of 0-1500 m (or up to 2100 m in some regions).'

CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.

2.04

'It is indigenous us to the American tropics, and is now naturalized throughout the tropics and subtropics.'

CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.

2.05

Has been introduced in many countries in the tropics and the subtropics.

CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.

3.01

(1) It is naturalized in Hawaii. (2) A major invasive species in the Galapagos Islands. Also a problem in the Marquesas, New Caledonia, Tonga and Fiji.

(1)Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu. (2)http://www.hear.org/pier/psgua.htm

3.02

3.03

(1) 'One disadvantage is that P. guajava is an important weed in pastures, where it is difficult to eradicate and leads to land degradation in some Pacific Islands and Central American.' (2) In Fiji the invasion of pasture land made livestock farming uneconomic in places (3) Despite its use commercially, guava is considered a weed in lower elevations in Hawaii. It is also a serious pest plant in pastures.

(1) CAB International, 2000. Forestry Compendium Global Wallingford, UK: CAB International. 2)http://www.bangor.ac.uk/~afs101/iwpt/web-sp16.htm (3)http://www.extento.hawaii.edu/kbase/crop/crops/i_guava.htm

3.04

(1) naturalized and often forming dense stands in disturbed dry, mesic, and wet forest (2) It is a serious environmental weed in the Galapagos, suppressing the native flora

(1) Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu. 2)http://www.bangor.ac.uk/~afs101/iwpt/web-sp16.htm

3.05

Psidium cattlenianum is an environmental weed in Hawaii.

Smith, C.W. 1985. Impact of alien plants on Hawaii's native biota. Eds. C. P. Stone & J. M. Scott. University of Hawaii.

4.01

The species does not produce thorns spines or burrs.

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu.

4.02

(1) 'The leaves are suspected of allelopathic activity.' (2) Exudates from guava root were found to inhibit the growth of weeds.

(1) Smith, C.W. 1985. Impact of alien plants on Hawaii's native biota. Eds. C. P. Stone & J. M. Scott. University of Hawaii. (2) Brown, R. L. C. S. Tang, R. K. Nishimoro. 1983. Growth inhibition from Guava root exudates. HortScience Vol 18 (3): 316 -318

4.03

Did not find any evidence on it being parasitic.

4.04

Probably unpalatable because invades heavily grazed pastures.

4.05

Probably not since cattle, pig, horses are known to disperse it. Did not find any direct evidence of poisoning in animals.

4.06

This source under 'fungal-host distribution' lists 222 fungus species to be found on P. guajava. Some are economically important. 2) Guava fruitfly is a serious pest of citrus

http://nt.ars-grin.gov/fungaldatabases/all/FindRecOneFungusFrame.cfm 2)http://creatures.ifas.ufl.edu/fruit/tropical/guava_fruit_fly.htm

4.07

'The roots, bark, leaves, and green fruit are used as medicine in the tropical world …whole leaves are chewed to relieve toothache.' Did not find any evidence on allergies.

Yadava, U. L. 1996. Guava (Psidium guajava L.): An exotic fruit with potential in the southern United States. HortScience Vol 31(5): 789 - 794.

4.08

No information.

4.09

1. 'Is intolerant of frost and deep shade but regenerates and grows quickly in gaps.' 2. can withstand partial shading

1.Cronk, Q. C. B. & J. L. Fuller. 1995. Plant invaders. Chapman and Hall. London. 2.http://www.bangor.ac.uk/~afs101/iwpt/web-sp16.htm

4.1

Compared to many other tropical fruit trees guava can tolerate a wide range of environmental and edaphic conditions.

Yadava, U. L. 1996. Guava (Psidium guajava L.): An exotic fruit with potential in the southern United States. HortScience Vol 31(5): 789 - 794.

4.11

The species in not a vine and I did not find any evidence to it having a smothering habit.

4.12

(1) '…in Hawaii naturalized and often forming dense stands in disturbed dry, mesic, and wet forests, …' (2) 'It invades disturbed sites and forms dense thickets.

(1) Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu. (2) Smith, C.W. 1985. Impact of alien plants on Hawaii's native biota. Eds. C. P. Stone & J. M. Scott. University of Hawaii.

5.01

5.02

5.03

The species is a small tree or shrub, 3- 10 m tall. No evidence of its ability to fix nitrogen

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu.

5.04

6.01

Did not find any evidence of reproductive failure in native habitat.

6.02

Grown from seeds.

6.03

Don’t know. Did not find any reference on hybridization.

6.04

'Self-pollination is conspicuous (60% to 75%) since many of the isolated trees produce satisfactory crop, however the distribution of cross pollination which …is estimated to be ~ 35%.'

Yadava, U. L. 1996. Guava (Psidium guajava L.): An exotic fruit with potential in the southern United States. HortScience Vol 31(5): 789 - 794.

6.05

'… the distribution of cross pollination which is carried out by insects and bees, is estimated … .'

Yadava, U. L. 1996. Guava (Psidium guajava L.): An exotic fruit with potential in the southern United States. HortScience Vol 31(5): 789 - 794.

6.06

'...and often producing suckers.' but does not lead to spatial spread.

CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.

6.07

R. Criley, UH Department of Horticulture, Personal communication (2) '… seedling trees of guava are not as precocious as vegetatively propagated trees, which can start fruiting in 2 to 3 years vs 4 to 5 years for seedling trees.'

(2)Yadava, U. L. 1996. Guava (Psidium guajava L.): An exotic fruit with potential in the southern United States. HortScience Vol 31(5): 789 - 794.

7.01

Humans consume fruit along hiking trails, often spitting out seeds.

Yadava, U. L. 1996. Guava (Psidium guajava L.): An exotic fruit with potential in the southern United States. HortScience Vol 31(5): 789 - 794.

7.02

Guava is a much relished fruit throughout the tropics and subtropics and it is very likely to be dispersed intentionally by people.

Yadava, U. L. 1996. Guava (Psidium guajava L.): An exotic fruit with potential in the southern United States. HortScience Vol 31(5): 789 - 794.

7.03

Seeds are relatively big - 1 to 4 mm in diameter and are yellowish to cream colored. May be unlikely to disperse as produce contaminant.

Yadava, U. L. 1996. Guava (Psidium guajava L.): An exotic fruit with potential in the southern United States. HortScience Vol 31(5): 789 - 794.

7.04

7.05

7.06

'The seeds are dispersed by alien fruigivorous birds as well as rats and feral pigs.'

Smith, C.W. 1985. Impact of alien plants on Hawaii's native biota. Eds. C. P. Stone & J. M. Scott. University of Hawaii.

7.07

'The seeds are dispersed by alien fruigivorous birds as well as rats and feral pigs.' Fruit is large with no means of seeds attaching externally

Smith, C.W. 1985. Impact of alien plants on Hawaii's native biota. Eds. C. P. Stone & J. M. Scott. University of Hawaii.

7.08

'The seeds are easily spread by cattle, horses, birds, and pigs … '

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu.

8.01

Probably yes. No direct reference on seed production but - '… guava also is a prolific and regular-bearing tree fruit that could produce fruit year round. Hundred+ seeds per fruit.

Yadava, U. L. 1996. Guava (Psidium guajava L.): An exotic fruit with potential in the southern United States. HortScience Vol 31(5): 789 - 794.

8.02

"Seeds remain viable for several months"

http://www.bangor.ac.uk/~afs101/iwpt/web-sp16.htm

8.03

(1) Three herbicides were mentioned is this book towards the control of guava. Under one of these herbicides it is cautioned that regrowth may occur. (2) 'Penetration by herbicides is limited by the waxy cuticle.'

(1) Swarbrick J. T. 1982. The Australian weed control handbook. Plant Press. Toowoomba. (2) Cronk, Q. C. B. & J. L. Fuller. 1995. Plant invaders. Chapman and Hall. London.

8.04

'Guava can survive moderately intense fires by regenerating from basal sprouts.'

Smith, C.W. 1985. Impact of alien plants on Hawaii's native biota. Eds. C. P. Stone & J. M. Scott. University of Hawaii.

8.05

Has spread widely in Hawai‘i already. 'It has not been evaluated for biological control and is unlikely to be because of commercial orchards on kauai and Hawaii.'

Smith, C.W. 1985. Impact of alien plants on Hawaii's native biota. Eds. C. P. Stone & J. M. Scott. University of Hawaii.